多振子声子晶体的低频特性研究

本文设计了一种由硅橡胶包覆层包裹4个钨振子的新型声子晶体结构,通过有限元法计算该结构的色散曲线、振动模态和传输损失谱。结果表明,该结构的带隙范围为18.85~225.28 Hz,与传输损失谱频率衰减范围相吻合,能够有效抑制20~200 Hz的弹性波在声子晶体中传播。通过分析色散曲线上点的振动模态,说明带隙产生的原因。本文讨论了声子晶体板的缺口角度和振子之间的纵向和横向间距对带隙的影响,结果表明:当缺口角度减小时,带隙下边界几乎保持不变,带隙上边界升高从而增加了带隙的宽度;振子之间横向或纵向间距增大时,带隙下边界和上边界均上升,带隙变宽,进而优化了声子晶体模型的带隙。同时声子晶体板的缺口设计能够节省材料,从而减轻结构的质量。     

Bit-rate Flexible Picosecond Pulse Width Conversion with All-optical Mono-stable Multivibrator Laser Diode

An optical mono-stable multivibrator laser diode (MM-LD) is realized by using a multi-electrode distributed feedback laser diode. All-optical pulse-width conversion of ultra-short pulses to non-return-to-zero (NRZ) is achieved using an MM-LD. The MM-LD is adopted for a wide range of bit-rates between 2-10 Gbit/s by tuning the DC bias. Data format transformation from 10-Gbit/s return-to-zero optical signals to NRZ optical-signals is achieved with error free operation. Converted optical signals, which have a narrower spectral bandwidth and lower peak power than when input, are transmitted using a 1.3-μm zero dispersion fiber (1.3Aλ₀-SMF).     

Analysis of emitter-coupled multivibrators by singularly perturbed systems

Emitter-coupled multivibrators play a decisive role in electrical engineering, especially for phase locked loops which are key-building blocks of analogue RF front-ends. Since multivibrators correspond to relaxation oscillators, in the following the modelling and analysis by the theory of singularly perturbed systems is presented. Models for fast and slow phenomena are derived, and the fast transients of emitter-coupled multivibrators are analysed for the first time. The results of our analysis lead to significant advantages for the design of electrical multivibrators.     

BEPCⅡ束团缺口信号的提取

 基于隧道二极管单稳态电路、高速可重触发电路、ECL技术等多种高速电路技术设计了BEPCⅡ束团缺口信号提取电路。介绍了BEPCⅡ储存环中带缺口的多束团运行模式。对Pickup电极感应信号经过长电缆传输衰减后的波形进行了研究。分析了缺口提取电路中处理快速信号的隧道二极管单稳态电路原理,该电路可以将0.3 ns的正脉冲展宽到4 ns的ECL电平脉冲。给出了标准束团注入和非标准注入情况下束团缺口判定逻辑。测试结果表明:此电路对各种束团注入情况均能正常工作,且提取出的同步信号均方根抖动值仅为80.49 ps,满足设计要求。     

Demonstration of Three True Random Number Generator Circuits Using Memristor Created Entropy and Commercial Off-the-Shelf Components

In this work, we build and test three memristor-based true random number generator (TRNG) circuits: two previously presented in the literature and one which is our own design. The functionality of each circuit is assessed using the National Institute of Standards and Technology (NIST) Statistical Test Suite (STS). The TRNG circuits were built using commercially available off-the-shelf parts, including the memristor. The results of this work confirm the usefulness of memristors for successful implementation of TRNG circuits, as well as the ease with which a TRNG can be built using simple circuit designs and off-the-shelf breadboard circuit components.     

Multipumping flow systems devoid of computer control for process and environmental monitoring

In this paper we describe for the first time the use of astable multivibrator circuits for computer-less control of solenoid micropumps and application for analytical flow techniques. Triggering and powering were accomplished using the NE555 integrated circuit. The activation and deactivation time intervals were adjusted using 10-turn trimmer potentiometers. The potential and characteristics of the instrumentation were studied on a two-channel flow system injecting an indigo carmine indicator solution. Subsequently, a three-channel flow system was assembled and successfully applied to the determination of nitrite in well waters. One circuit was used to control the activation time intervals of three further circuits used for the control of the flow rates or pulsation of solenoid micropumps. These were used for driving carrier, reagent, and sample in an analytical flow system. In the present work, the utility of the circuits for the construction of simple multipumping flow systems was demonstrated. A main feature to be highlighted was the simplicity and very low costs of the controlling circuits, favouring economic and miniaturised flow analysers. Second, no expenses or knowledge are required for the usual software control of the solenoid micropumps. This allows working with every existing detector without considering any problems of software and control compatibility. Third, owing to these features, the proposed assembly is especially suited for simple monitoring analysers, sample provision from an environmental or industrial process, or chemical education.     

双边沿单稳态触发器的设计

对双边沿单稳态触发器的设计原理进行了研究，根据双边沿单稳态触发器工作特点的要求，以RC电路为定时单元，提出了积分型和微分型双边沿单稳态触发器的基本结构，阐明了双边沿单稳态触发器的设计方法，并具体设计了积分型和微分型双边沿单稳态触发器。     

基本触发器、单稳态电路及多谐振荡器的统一设计和教学方法研究

针对一般教科书缺乏对基本触发器、单稳态电路及多谐振荡器设计方法的论述问题,从电路存储信号需求出发,研究了基本触发器、单稳态电路及多谐振荡器间的内在联系,发现通过在基本触发器的支路中接入电容,由电容的充放电实现单稳态电路及多谐振荡器,从而提出了基本触发器、单稳态电路及多谐振荡器的统一设计方法,并在课堂上讲授。这不仅有利于学生学习和掌握这3种电路的设计方法,深入理解这3种电路的工作原理,而且可培养学生探索事物本质及其内在联系的能力。